elevated slab... anyone done one

[GSRinmyCRX]

i am in preliminary stages of my house building plans and we have been kicking around doing an elevated slab for the 2-car garage to give a lot of additional storage in the basement.

has anyone done one? have any advice, difficulty, cost, etc.?

Thanks.

Levi

 

[readhead]

Do a search. There have been several threads recently. I do them quite often. The engineer doing the plans should have no problem doing a design.

 

[wssix99]

They are expensive and require maintenance, particularly if you live in a snow area.

I lived in a condo for a while with elevated slabs and we were constantly chasing down snow melt leaks through the cracks. (Cracks form in all concrete slabs.)

You can seal the slab or cover it with a membrane, but that's just more cost and maintenance. You'll probably find that putting your storage above the parking pad is more economical.

 

[readhead]

Expensive is relative to the desired outcome. There should be no maintenance if installed correctly.

This is common construction for commercial work. If the slab needs to be waterproof it can have a membrane below or be poured with a higher cement mix. Keep in mind septic tanks don't leak.

Cracks do not form in all concrete slabs. If installed correctly there is no reason for a slab to crack. It takes a lot of care to prep and place a slab to not crack. It is not like a driveway where you pour and finish and walk away.

 

[wssix99]

Keep in mind septic tanks don't leak.

I wouldn't park under or store my stuff under one of those, either. lol

If installed correctly there is no reason for a slab to crack.

All concrete cracks. This is concrete 101. Reinforced slabs, like reinforced septic tanks just have really really small cracks. (Hopefully so small they don't leak so bad.) If designed a certain simple way, the slab can be lower maintenance. The worse situations I've seen had integral reinforced concrete posts/columns, which made things a lot more complex.

 

[hh76]

Just built, and looked into it for a shop under. My brother just did it on his house, so I was pretty confident with my numbers.

My garage is 26x42' to get the space under would have cost an additional $15-17,000. That would be with me doing some work. Keep in mind that in WI, I would already have been putting in 4' frost walls, so it would have only have been adding 5' to the poured walls.

I didn't do it, mostly because I couldn't get good access to it without really manipulating the grade, which didn't fit the rest of the house plan. I didn't want to have my only access to it to be down a set of stairs.

My brother loves his, although he is really kicking himself for not installing in floor heat. No leaks, it was installed correctly, with a membrane under the upper slab. Garage floor was properly pitched, no issues.